Excuse or Reason
What is the difference between an "Excuse" and a "Reason"?
Well, just my opinion, but I would say that the difference between the two is that, an excuse is something that you could have done but you are looking for something to explain why you couldn't. In other words, it is just away of explaining away either laziness or forgetfulness, or even lack of want to do something (man made reason)
Where as, a reason, is something to explain away why you haven't done something or been somewhere because it has been beyond your choice or control, and you would have done it if you could, or would have been there if you could have been.(course of life actions stopping you)